Means for and process of forming locks for plaster



DGC. 19, 1922.

C. A. SMITH.

ME'ANS FOR AND PROCESS OF FORMING LOCKS FOR PLASTER.

FILED AUG. 15, I92].

Concrete Fig. 4.

' Fig fi.

Charles A Smith, J;

Au; @bbommfS Patented Dec. 19, 1922.

CHARLES A. SMITH, OF COLUMBUS, OHIO.

.MEANS FOR AND PROCESS OF FORMING LOCKS FOB, PLASTERI.

Application filed August 15, 1921. Serial No. 492,278.

To all whom alt-may concern Be it known that I, CHARLES A. SMITH, a citizen of the United States, residing at Columbus, in the county of Franklin and State of Ohio, have invented a certain new and useful Improvement in Means for and very difficult to make plaster stick to concrete because of the powdery surface of the latter and as a consequence much trouble, annoyance and expense has been occasioned.

The object of the present invention is to provide a construction and process by the use of which the plaster may be effectually and permanently secured to the concrete.

Broadly stated the invention consists in providing the concrete with effective looking dovetail or equivalent recesses into which the laster is keyed.

T e invention is embodied in the example herein shown and described, the features of novelty being finally claimed.

In the drawings- Figure 1 is a transverse sectional view of several of the lock molding strips showing them connected b a flexible strip.

Fig. 2' is a sectlonal view showing a concrete wall molded with the device as shown in Fig. 1.

Fig. 3 is a sectional view of a fraction of concrete wall with one of the lock molding strips partly removed from the plaster lock.

Fig. 4 is a sectional view showing a molding strip wholly removed from the lock and plaster keyed to another look after removal of the molding strip.

Fig. 5 is a plan view illustrating how the lock molding strips are connected together.

In the views 6 desi nates a lock forming strip which is prefera ly made of wood of dovetail cross section and provided with two deep lon itudinal saw kerfs 7 and 7 so as to provi e a central portion 8 that is easily severable from the two triangular wings to effect the destruction or deformation of the str1p without alterin the lock. The strips 6 are connected toget er in suitable lengths for collective and convenient handling by means of thin metallic'strips 9 lightly nailed to the narrow faces of the strips as shown in Fig. 5.

In practice the lock molding board 10 with the narrow faces of the strips are placed adjacent the board, as shown in Fig. 2, and the concrete to make the body of the wall or ceiling poured so as to surround the strips. After the concrete of the wall has set the form board is removed as are also the metallic connecting strips 9; the middle portions 8 of the moldmg strips between the saw kerfs are then pried out with a suitable tool, as shown 1n Fig. 3, after which the triangular portions are easily removed leaving the clear lock groove of dovetail form as shown at the left hand side of Fig. 4. When, in a given wall or ceiling. all the molding strips have been removed a surface. ispr'esented containing an ample number of parallel dovetail. locking grooves over and into which the plaster coat can be applied as shown at the right hand side of Fig. 4, with assurance that it will stick when dried because the plaster is keyed to the wall and reliance is not had solely upon anv adhesive quality of the plaster.

When a suitable number of the lock molding strips are tied together in parallel rela- I tion by flexible metallic strips as shown in Fig. 5 the product can be rolled up into a bundle that is easily handled and transported.

The form of the dovetailed parts can be changed without departing from the gist of the invention as claimed.

' What I claim is:

1. The art of preparing a concrete wall or ceiling for a plastic coat consisting in forming in said wall or ceiling by suitable molding strips, a plurality of undercut recesses and subsequently removing said molding strips by destruction of them;

2. Means for molding in a concrete wall or ceiling an undercut lock for a plastic coat consisting of dovetailed strip ofwood having a longitudinal kerf.

3. Means for forming in a wall or ceiling a lock for a plastic coat consisting of a dovetailed strip of wood having two longitudinal kerfs forming an intermediate re 5 movable portion.

4. An article of manufacture for the purpose set forth consisting of a plurality of dovetailed strips of Wood each having two longitudinal kerfs forming an intermediate removable portion and means cminoeting 10 said strips together.

5. An article. of manufacture for the purpose Statecl consisting of a plurality of (leformable dovetailed strips and means attached to the narrow faces of said strips for 15 connecting them together.

CHARLES A. SMITH. 

